package demo2;

public class Computer {
    public void powerOn(){
        System.out.println("打开电源");
    }

    public void powerOff(){
        System.out.println("关闭电源");
    }

    public void useDevice(USB usb){
        usb.openDevice();

        if(usb instanceof Mouse){
            Mouse mouse =(Mouse)usb;
            mouse.click();
        } else if (usb instanceof Keyboard) {
            Keyboard keyboard = (Keyboard)usb;
            keyboard.useKeyboard();
        }

        usb.closeDevice();
    }
}
